Hello.I'm made ARDUINO SEVERINO SERIAL SINGLE SIDED VERSION 3 S3v3 (REVISION 2), but i can't find atmega8-16, can i use atmega8L-8pu in this version of arduino?[sorry, i'm russian, and my english not well as i want]

You can, but keep in mind that they are not guaranteed to run on 16 MHz. They usually do, though. You can also substitute an ATmega168-10PU or an ATmega328P-20PU, both can easily run at 16 MHz and have Arduino-compatible firmwares shipped with the Arduino client software.